814779821 has 2 divisors, whose sum is σ = 814779822. Its totient is φ = 814779820.

The previous prime is 814779811. The next prime is 814779857. The reversal of 814779821 is 128977418.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 794619721 + 20160100 = 28189^2 + 4490^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-814779821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (814779811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 407389910 + 407389911.

It is an arithmetic number, because the mean of its divisors is an integer number (407389911).

Almost surely, 2^814779821 is an apocalyptic number.

It is an amenable number.

814779821 is a deficient number, since it is larger than the sum of its proper divisors (1).

814779821 is an equidigital number, since it uses as much as digits as its factorization.

814779821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 225792, while the sum is 47.

The square root of 814779821 is about 28544.3483197638. The cubic root of 814779821 is about 933.9997390208. Note that the first 3 decimals are identical.

The spelling of 814779821 in words is "eight hundred fourteen million, seven hundred seventy-nine thousand, eight hundred twenty-one".